Crystal Rod Doping Control for Axial Resistivity Uniformity
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Solution Overview
Problem
The Czochralski method for producing single-crystal silicon faces challenges in controlling axial resistivity and uniformity, leading to reduced minority carrier lifetime and cell conversion efficiency due to high oxygen content and crystal defects.
Innovation Solution
A method and device for controlling crystal rod axial resistivity by determining stibium evaporation amounts in different stages of the Czochralski process using correlation relationships and calculation models, ensuring accurate doping ratios of stibium and phosphorus to achieve uniform resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Czochralski method is used to produce single-crystal silicon, then production cost is reduced and large quantities can be produced, but axial resistivity is difficult to control and crystal defects increase
Solution Approach 1:
The patent divides the crystal growth process into multiple stages (seeding stage, shouldering stage, uniform growth stage) and applies different doping strategies to each stage. By segmenting the growth process and controlling stibium evaporation at different phases, the method achieves uniform axial resistivity while maintaining high productivity of the Czochralski method.
Solution Approach 2:
The patent dynamically adjusts doping parameters (stibium evaporation amount, phosphorus doping amount) based on real-time monitoring of crystal weight and growth stage. This parameter adjustment strategy enables precise control of axial resistivity uniformity while preserving the high production efficiency of the Czochralski process.
2Ease of manufacture
If high oxygen content is present in single-crystal silicon, then production is easier, but oxygen donors cause attenuation of cell conversion efficiency
Solution Approach 1:
The patent introduces stibium as an intermediary element that interacts with oxygen in the crystal structure. By controlling stibium evaporation and doping, the method mitigates the harmful effects of oxygen donors on cell conversion efficiency while maintaining the ease of manufacture associated with high oxygen content crystals.
3Device complexity
If stibium evaporation is not controlled, then doping process is simpler, but axial uniformity of dopant elements deteriorates
Solution Approach 1:
The patent implements a feedback control system that monitors crystal weight and growth stage in real-time, then adjusts stibium evaporation rates accordingly. This feedback mechanism ensures precise control of axial dopant uniformity without significantly increasing doping process complexity, as the control is integrated into the existing growth process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves the axial uniformity of dopant elements in single-crystal silicon, achieving accurate control over resistivity and enhancing the quality of Czochralski crystal rods.
Implementation Method 1
determining a first stibium evaporation amount in a stibium-phosphorus co-doped single-crystal growth furnace
Data Source
Figure 1
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AI summary
Disclosed are a method and a device for controlling crystal rod axial resistivity. The method includes: determining a first stibium evaporation amount in an equal-diameter growth process according to a first correlation relationship between a stibium evaporation velocity and a remaining-material weight, and controlling a stibium-phosphorus doping ratio in the equal-diameter growth process according to the first stibium evaporation amount; determining a second stibium evaporation amount in a seeding and shouldering process according to a second correlation relationship between the stibium evaporation velocity and a seeding and shouldering duration, and controlling the stibium-phosphorus doping ratio in the seeding and shouldering process according to the second stibium evaporation amount; and determining a third stibium evaporation amount at a re-charging stage according to a target re-charging evaporation calculation model , and controlling the stibium-phosphorus doping ratio at the re-charging stage according to the third stibium evaporation amount.